Dreamhost just sent me an email about their plans to move an entire hosting cluster, resulting in downtime for over 8 hours - if all goes well. Its stuff like this that makes me not like using shared hosts. Here's a copy of the email:
Due to space and power constraints in our primary datacenter we are moving the entire shared cluster spacey to our LAX facility at 10:00PM PST (GMT - 8), two weeks from today, Friday, November 30th 2007. All webservers, mail servers, file servers, and MySQL servers in the spacey cluster will be unreachable during the move, which we expect to take approximately 8 hours.
Receiving this email means the downtime window will affect your site(s). To double check your cluster, you can go to the Account Status button on the upper right hand of the webpanel ( https://panel.dreamhost.com ) you should see your cluster under the section Your Email Server:.
We do apologize for this inconvenience. Rest assured we will do everything possible to keep downtime to a minimum.
If you have any questions regarding the server move, please contact our support team.